1. Melt chocolate over low heat.
2. Gradually stir in cocoa powder and milk while continuing to heat. You want the consistancy to be thick but not solid as you add the milk and cocoa powder.
3. Beat sugar into eggs.
4. Stir hot chocolate/milk mixture into eggs.
5. Add cream and vanilla extract. Cool.
6. Just before adding to ice cream maker, stir a cup of ice cream mixture into peanut butter. Once mixed, stir into rest of ice cream mixture.
7. Freeze in ice cream maker according to manufacturer's instructions.
I used the odd mixture of chocolate because that's what I had available.
Use fresh ground peanut butter if possible (ie, it should be 100% peanuts).